@jyjjy, mousemonkey told me opposite
I'm more inclined to believe jyjjy on this one.
People have been telling us that you can't unlock anything but the reference models, but I am able to unlock the MSI R6950 Twin Frozr II. The card would not work with a reference bios either.
However, the shader unlock just requires you to alter the existing bios where it determines how many shaders are unlocked. I see no reason it wouldn't work, and I've also heard there are people that have been successful doing it with the 1gb versions.